Writing instrument



FIG. 1 is a front elevational view thereof in accordance with my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a right side elevational view thereof, with the left side elevational view being a mirror image thereof;

FIG. 4 is a bottom plan view thereof; and,

FIG. 5 is a rear elevational view thereof.

The lower portion of the writing instrument barrel depicted by means of broken lines in FIGS. 1, 3, 4 and 5 has been shown for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a writing instrument, as shown and described. 